Variable displacement pump



arm/Mir .INVENTOR. BY 7eier Jchen/C P. SCHENK VARIABLE DISPLACEMENT PUMP Filed Aprll 2'7, 1948 Oct. 3, 1950 Patented Oct. 3, 1950 UNITED STATES A PATENT I OFFICE 7 Claims.

r This invention relates to pumps and particularly to those employed for feeding or delivering fluids in predetermined quantities.

One of the objects of the invention is to provide a pump of this character by means of which the quantity of fluid delivered or displaced by each piston stroke can be regulated or varied to suit operating requirements.

More particularly, the invention contemplates the provision of a cylinder in which a piston is reciprocable, the piston being provided with an axially-extending aperture or recess, and the cylinder having an adjustable member regulatable as to the extent to which it projects into the cylinder and being thus adjustable to and from the apertured or recessed end of the piston so that said member can enter at a predetermined and selected point in the stroke of the piston and thereby determine the point at which the fluid in the cylinder will begin to be displaced out of the cylinder by the piston.

In the accompanying drawing, wherein several illustrative embodiments of the invention are disclosed:

Fig. 1 is a sectional view through a pump constructed according to the invention;

Fig. 2 is a similar sectional view of another embodiment of the invention, and

Fig. 3 is a view showing a third embodiment of the invention.

Referring to the embodiment of the invention shown in Fig. 1, i indicates the body or" a cylinder having the piston chamber :2 in which a pis ton 3 is reciprocable. The piston can be of any suitable construction, and is provided with a wrist-pin 4 on which is journalled the connecting rod 5, the opposite end of the connecting rod being pivotally connected to the crank shaft l in the known manner. The elements thus far described may be of any known or conventional construction.

The fluid supply may consist of a tank or reservoir 8 connected by suitable conduit 9 to an inlet passage ll! leading into the piston chamber 2. Provided in the inlet passage 2 is a check valve l I normally maintained closed or against its seat I3 by a spring l2 on the upstroke or delivery movement of the piston 3.

Also communicating with the piston chamber 2 is the outlet passage M which is provided with a seat l5 against which a check valve i6 is nor mally maintained by means of the spring [8 and particularly on the downstroke or non-delivery movement of the piston.

Provided through the piston 2 is a centrally located, axially extending aperture I 9 which normally establishes communication between the piston chamber 2 and the crank case 2|] located below the cylinder l. Adjustably mounted above the piston 3 and in axial alignment with the aperture I9 extending therethrough is a rod or control pin 25 of a diameter and shape enabling it to closely fit within the aperture l9 to any required extent to thereby control the quantity of fluid forced through the outlet passage lion each upstroke or feeding movement of the piston. This rod or control pin is mounted to be adjustable through the head of the cylinder l inany suitable manner, such as by being threadably mounted in a part of the cylinder or in a suitable support, or its projection into the pistonl chamber to any required extent can be controlled by cams or other means. i It is sufiicient to state that the pin is adjustable axially so that any required portion of it can be projected into the interior of the cylinder 2 to regulate the quantity of fluid to be displaced by the piston on each upstroke of the same in a manner to be explained.

The interior of the crank case is connected to the inlet passage 10 at a point outside of the check valve H by a communicating passage 22.

Briefly, the operation of the device is as fol--' lows: The quantity of fluid to be displaced by the piston and forced thereby out through the outlet passage I4 is determined by the extent to which the rod or control pin 2|. protrudes into the piston chamber 2.

Assuming, for example, that the rod or control pin is located in an elevated or raised position with its lower end substantially flush with the top inner surface of the piston chamber 2. In such a case, when the piston moves upwardly, no fluid will be displaced out of the chamber 2 through outlet [4. Instead, any fluid in the chamber will be forced downwardly through the aperture l9 and will pass down through the same into the crank case 20.

When the control pin 2| is so disposed that it projects into the piston'chamber, it will be noted that when the piston rises it will, at a point in its rising movement depending upon the position of the end of the control rod 2! in the chamber2, begin to surround the rod 2| which will fit within and close the aperture I 9. The aperture l9 being then closed by the pin 2|, the piston willthen exert pressur on the fluid in the chamber 2 and will force it against the check valve Hi to thereby open said valve and allow the fluid to be forced out through the outlet passage l4. .As the piston descends, it will create a suction, as long as the aperture I9 is closed by the pin 2|, thus causing the check valve l l to be opened and liquid drawn past the same into the piston chamber 2. When the piston descends to a point located below the end of the pin 2|, suction through inlet ill will end and the intake of the fluid will be discontinued. On the upstroke of the piston the forcing of fluid out of the piston chamber 2 and out of the outlet passage M by the piston will not take place until the piston reaches a point in its upstroke where the pin 21 enters and closes the aperture l9. As soon as the aperture I9 is closed, the piston will begin to urg the fluid in the chamber 2 toward the outlet passage It. The pressure of the fluid so moved against the check valve H will open the valve so that the fluid can pass it and flow out of the passage 14 and into a conduit connected thereto to a point of application.

It will be obvious from the foregoing that since the central aperture l9 through the piston 3 will remain open as long as it is not closed by the entry of the control pin 2|, the point at which the pin begins to enter the aperture l9 on the upstroke of the piston determines the quantity of fluid that is displaced from the piston chamber 2 on each upstroke of the piston. Hence, by adjusting the rod or pin 2! to provide a predetermined extent of projection into the chamber 2, the precise amount of fl-uid to be ejected by each upstroke of the piston can be accurately regulated.

In the embodiment of the invention shown in Fig. 2, the structure is generally similar to that shown in Fig. 1 except that the piston 3 is provided with an aperture 30 which extends only part way through it. The aperture 33 is formed with lateral branches 3|, 32 in communication with an annular groove 33 in the face of the piston, said groove being in constant communication with one end of a passage 34 which has its opposite end in communication with the inlet passag ill outwardly of the check valve ll. On the, upstroke of the piston, the fluid in the piston chamber 2 will be displaced down through aperture 30 and out through the communicating passages 3l, 32, 33 and 34 until the control pin 2! enters the aperture 33 and when this occurs, said aperture 30 will be closed off from communication with the piston chamber 2 and hence any fluid in the chamber 2 will then, upon further rising movement of the piston, be forced out of the outlet passage l4.

Another embodiment of the invention is disclosed in Fig. 3, wherein the piston 3 has an aperture 35, more accurately described as a recess since it is open at one end only, and the control pin or rod, indicated at 33, is tubular or hollow for a portion of its length, thus providing an axial passage 3'! formed at its upper end with lateral outlets 38 in constant communication with an annular channel 39 in the cylinder head. A passage 40 establishes communication between said channel 39 and the inlet passage ill outwardly of the inlet check valve H. With this arrangement the piston on its upstroke, and while it is moving up wardly below the end of the pin 36, will force the fluid up through the passage 3'3 in the pin, and out through the lateral outlets 38 to reach the passage 40. However, as soon as the pin 33 begins to enter the aperture 35, communication between the passage 3? and the piston chamber 2 will be shut off so that on the continuing upstroke of the piston the fluid in the piston chamber 2 will open the check valve i6 and flow out of the outlet passage 14.

It will be clear from the foregoing that in each of the embodiments shown, the quantity of fluid displaced by the piston on each of its upstrokes will be determined by the extent to which the control pin or rod projects into the interior of the cylinder in which it is mounted. Thus, by shifting the pin so that it is moved away from the end of the piston a decreased flow of the fluid out of the pump will be the result, and by causing the pin to be adjusted inwardly or toward the piston, an increased amount of fluid will be displaced. As previously stated, the position of the control pin may be regulated in various ways, either manually or mechanically according to the installation of the pump, the particular environment in which it is used or the purpose to which it is put. Also, while I have described the pump in single cylinder construction, it is obvious that a multicylinder arrangement is both possible and entirely practical.

In herein referring to the opening in the piston in which the control pin enters at a predetermined point in the stroke of the piston, I have referred to said opening as an aperture and despite the fact that in several of the embodiments described, this opening is closed at one of its ends. In View of this, I, therefore, wish to be understood, when referring to the opening as an aperture, as meaning not only an opening which extends clear through the piston, but any recess, depression or formation which permits by the entry of an adjustable regulating element the control of the point at which the piston will begin the displacement of the fluid out of the piston chamber.

While I have herein described several embodiments of the invention, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What I claim is:

1. In a pump of the character described, a cylinder, means for supplying fluid into the cylinder, a piston reciprocable therein for displacing fluid out of the cylinder, said piston being provided with an aperture in communication with the interior of the cylinder, an element entering into the cylinder and adjustable to and from the aperture therein to enable it to be fixedly held at any position of desired projection into the cylinder, said element being capable of entering into the aperture at a selected point in the stroke of the piston, the extent of the projection of the element int the cylinder determining the amount of fluid displaced by the piston from the cylinder on its movement toward said element.

2. In a pump of the character described, a cylinder, means for supplying fluid into the cylinder,

piston reciprocable within the cylinder for displacing fluid c-ut of the cylinder, said piston having an aperture extending axially through it, a control element entering the cylinder and adjustable axially of the same to enable it to be fixedly held at any position of desired projection into the cylinder, said element being capable of entry into the aperture in the piston to a selected extent on the stroke of the piston toward said element to thereby determine the amount of fluid displaced by the piston on its movement toward said element.

3. In a pump of the character described, a cylinder, means for supplying liquid into the same, a fluid outlet from said cylinder, a piston reciprocably mounted in the cylinder, the piston being provided with a passage extending through it, a

incler having an inlet, a check valve therein, said cylinder having an outlet, a check valve therein, a piston mounted for reciprocation within the cylinder, said piston having a central aperture, a stationary pin entering the end of the cylinder and adapted, at a selected point in the movement of the piston, to enter and close the aperture but permit sliding movement of the piston relative to the stationary pin, whereby said pin upon closing the aperture in the piston causes the piston to become effective to force fluid in the cylinder to open the outlet check valve to pass said fluid out of the outlet.

5. In a pump, a cylinder, a piston reciprocable therein, said piston having a central aperture, a, pin adjustable in the cylinder and closely fitting the aperture in the piston and regulatable as to the extent of its projection into the interior of the cylinder and into the aperture in the piston, whereby said pin may be set to close the aperture in the piston at any selected point in the stroke of the piston.

6. In a pump, a cylinder, a piston reciprocable therein, said piston having an aperture open at one end, a stem adjustable through the cylinder to position its inner end fixedly at any selected point in the cylinder to thus regulate the extent to which said stem projects into the cylinder, said stem fitting the aperture in the piston, the stem having an axial bore open at one end and communicating at its other end with a passage leading out of the cylinder.

7. In a pump,a cylinder, provided with a piston chamber, a, piston mounted for reciprocable movement in said chamber, an inlet passage leading into the cylinder, a check valve in said inlet passage permitting the now of fluid into the piston chamber on ascent of the piston, an outlet passage leading from the piston chamber, check valve in said outlet passage permitting the flow of fluid out of the piston chamber upon descent of the piston, the piston being provided with a central aperture, and an adjustable pin regulatable through the head of the cylinder and adjustable to or from the piston to thereby fixedly locate its inner end at any selected point in the cylinder to determine the point at which the pin will enter and close the aperture in the piston on the ascent of the piston.

PETER SCHENK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,019,650 Bischof Nov. 5, 1935 2,020,302 Deschamps Nov. 12, 1935 2,206,914 Muller et a1. l- July 9, 1940 2,433,222 Huber Dec. 23, 1947 

